Ferroelectric thin film element

Abstract

A ferroelectric thin film element 1 constructed by forming a MgO thin film 3 oriented in the direction (100), a lower electrode 4 composed of an alloy thin film of a Ni--Cr--Al system oriented in the direction (100), a ferroelectric thin film 5 composed of a PbTiO 3 thin film oriented in the direction (111), and an upper electrode 6 in this order on a substrate composed of (100) silicon 2.

What is claimed is: 
     
       1. A ferroelectric thin film element comprising: a monocrystalline substrate composed of (100) crystal plane oriented silicon;   a crystalline MgO thin film formed on said silicon substrate and oriented in the (100) crystal plane;   a crystalline lower electrode formed on said MgO thin film and composed of an alloy thin film of Ni--Cr--Al alloy or an alloy thin film of Ni--Al alloy oriented in the (100) crystal plane;   a crystalline ferroelectric thin film of PbTiO 3  system or Pb (Ti 1-x  Zr x ) O 3  system formed on said lower electrode and oriented in the (111) crystal plane; and   an upper electrode formed on said ferroelectric thin film.   
     
     
       2. The ferroelectric thin film element according to claim 1, wherein said lower electrode composed of the alloy thin film of Ni--Cr--Al alloy or the alloy thin film of Ni--Al alloy is deposited on said MgO thin film by sputtering. 
     
     
       3. The ferroelectric thin film element according to claim 1, wherein said ferroelectric thin film is deposited on said lower electrode by sputtering. 
     
     
       4. The ferroelectric thin film element according to claim 1, wherein said upper electrode is composed of the same alloy thin film as the alloy thin film composing said crystalline lower electrode. 
     
     
       5. The ferroelectric thin film element according to claim 1, wherein said lower electrode is composed of an alloy thin film of Ni--Cr--Al alloy oriented in the direction (100) crystal plane. 
     
     
       6. The ferroelectric thin film element according to claim 1, wherein said lower electrode is composed of an alloy thin film of Ni--Al alloy oriented in the (100) crystal plane. 
     
     
       7. The ferroelectric thin film element according to claim 6 in which the alloy thin film contains 2.5 to 8% aluminum. 
     
     
       8. The ferroelectric thin film element according to claim 7 wherein said upper electrode is composed of the same alloy thin film as the alloy thin film of said crystalline lower electrode. 
     
     
       9. The ferroelectric thin film element according to claim 5 wherein said alloy thin film contains 8 to 25% chromium and 2.5 to 8% aluminum. 
     
     
       10. The ferroelectric thin film element according to claim 9 wherein said upper electrode is composed of the same alloy thin film as the alloy thin film of said crystalline lower electrode.